In general, aircraft landing gear is retractable, and for this purpose includes driving actuators (hydraulic actuators, electrical actuators, locking hooks, . . . ) which control extension and retraction of undercarriages and also of doors for the wells that receive the undercarriages when retracted. An airplane carries various position sensors adapted to identify the positions of the undercarriages and of the doors, with information therefrom serving to implement determined logic for extending or retracting landing gear that is initiated in response to a pilot order.
The undercarriages of an airplane, and in particular the nose wheel, also include moving parts adapted to enable the wheels to be steered to enable the airplane to be moved on the ground. To this end, the airplane has steering actuators (hydraulic actuator, electric motor, . . . ) adapted to steer the steerable wheels. The airplane also has various sensors (for sensing wheel angular position, speed, . . . ) delivering information used for implementing steering servo-control for steering the wheels in response to a steering instruction from the pilot.
The undercarriages of an airplane also carry brakes which comprise braking actuators (hydraulic pistons, pushers controlled by electric motors, . . . ) for selectively applying braking force on friction disks adapted to slow rotation of the wheels. The airplane carries various sensors (speed of wheel rotation, braking intensity, . . . ) delivering information that is used for implementing braking servo-control adapted to apply a given braking force to the wheels in response to a braking instruction from the pilot. The servo-control includes an antilock function for relaxing the braking force on a wheel if it begins to skid.
Those various actuators are controlled by a landing gear management system.
In a known architecture for a landing gear management system, the management system has a braking computer (generally including an active channel and a monitoring channel) for controlling the braking actuator, a steering computer for controlling the steering actuator, and a maneuvering computer for controlling the extension and retraction actuators. Each of the computers is connected via simple point-to-point links to the sensors needed for implementing the associated function, one of the computers possibly being connected to another computer in order to provide it with some particular information, such as, for example, an indication that it is working or not working.
That type of architecture requires a large number of cables, and it requires any computers that manage critical functions, such as braking, to be duplicated.
Another example of known prior art, e.g. as used for the A380, is known as integrated modular avionics. The functions of steering and of maneuvering the landing gear are integrated in central computers of the airplane which are in communication with data concentrators via one-way communications buses of the ARINC 429 type. The computers are connected to one another via an asynchronous both-way bus of the AFDX type enabling data to be transferred between computers. However braking, and particularly antilock servo-control, continues to be performed by a specific computer not integrated in the central computers of the airplane and located remotely so as to be in the vicinity of the brakes in order to be in direct communication with the associated sensors.
That architecture remains non-uniform with specific computers located in unsecure locations on the airplane and requiring local connections that are not integrated in the communications network.
In the automotive field, braking architectures are known in the form of synchronous communications networks in which a control unit integrating antilock servo-control controls braking actuators connected to the synchronous communications network, with sensors associated with the brakes also being connected to the communications networks. The synchronous communications networks that have been described (e.g. of the TTP type or the FLEXRAY type) present a transmission speed and a method of managing transmissions that are compatible with the speed and stability required for antilock servo-control.